Question 1

Describe the differences between batch culture and growth in a chemostat. What are the advantages of a chemostat?

Accepted Answer

Batch culture represents growth in a closed system. At some point one or more essential nutrients will be depleted, or waste products will become insurmountable, both of which, of course, would lead to cessation of growth of the organism and eventually to cell death. Chemostatic growth regulates the flow of nutrients in, and the collection of wastes out, so that growth may be maintained at the exponential stage. For industrial purposes, a chemostat is a plus when one is collecting a cellular product that is produced during exponential growth. It would be desirable to maintain the organism in conditions where it would produce the most product.

Question 2

Mannitol salt agar (MSA) contains 7.5% NaCl, the carbohydrate mannitol and the pH indicator phenol red. Some organisms can ferment mannitol, producing acids as a by-product. Is this medium likely to be selective and/or differential? Explain.

Accepted Answer

Since MSA has such a high percentage of salt, it is selective for organisms that are salt tolerant and inhibits organisms that can't tolerate it. MSA is also differential for mannitol fermentation. Some organisms ferment mannitol to produce acids, which causes the pH to drop. The pH indicator will then turn a different color to indicate that the mannitol has been fermented. Organisms which can't ferment mannitol will not cause the medium to change color.

Question 3

Which of the following is NOT true about the substrate binding protein (SBP) of the ABC transport system?

Accepted Answer

A)  It is found in the periplasm of Gram-negative cells. 
B)  It is found tethered in Gram-positive cells. 
C)  It binds to the periplasmic face of the channel and releases the solute. 
D)  It snags the appropriate solute. 
E)  It is required for both the uptake and efflux systems. 
A)  It is found in the periplasm of Gram-negative cells. 
B)  It is found tethered in Gram-positive cells. 
C)  It binds to the periplasmic face of the channel and releases the solute. 
D)  It snags the appropriate solute. 
E)  It is required for both the uptake and efflux systems. E

Question 4

During biofilm formation, as more and more cells bind to the surface, they begin sending signals to each other in a process called:

Accepted Answer

A)  quorum sensing 
B)  homoserine lactone 
C)  siderophores 
D)  polysaccharides 
E)  symbiosis 
A)  quorum sensing 
B)  homoserine lactone 
C)  siderophores 
D)  polysaccharides 
E)  symbiosis

Question 5

During which stage of bacterial growth is the culture growing exponentially?

Accepted Answer

A)  lag 
B)  early log 
C)  late log 
D)  stationary 
E)  death 
A)  lag 
B)  early log 
C)  late log 
D)  stationary 
E)  death

Question 6

All known microorganisms have a set of genes coding for __________, whose DNA sequences are highly conserved across the phylogenetic tree.

Accepted Answer

A)  ribosomes 
B)  chloroplasts 
C)  enzymes 
D)  cell membranes 
E)  cell walls 
A)  ribosomes 
B)  chloroplasts 
C)  enzymes 
D)  cell membranes 
E)  cell walls

Question 7

The most widely used solidifying agent is __________, which is derived from seaweed.

Accepted Answer

A)  agar 
B)  gelatin 
C)  starch 
D)  cellulose 
E)  glycogen 
A)  agar 
B)  gelatin 
C)  starch 
D)  cellulose 
E)  glycogen

Question 8

A cafeteria worker who fails to wash his hands thoroughly and fails to wear gloves inoculates a quiche with 4 E. coli when he uses his finger to test whether it is done. By the time you purchase the quiche, there are 128 E. coli cells in it. How many generations did the cells go through?

Accepted Answer

A)  4 
B)  5 
C)  8 
D)  32 
E)  64 
A)  4 
B)  5 
C)  8 
D)  32 
E)  64

Question 9

Why is iron so often a limiting nutrient when it seems to be so abundant and how can organisms overcome this problem?

Accepted Answer

Iron is usually not free in nature but l

Question 10

Which form of transport occurs only in prokaryotes?

Accepted Answer

A)  facilitated diffusion 
B)  ABC transport 
C)  siderophores 
D)  group translocation 
E)  endocytosis 
A)  facilitated diffusion 
B)  ABC transport 
C)  siderophores 
D)  group translocation 
E)  endocytosis

Question 11

Which form of transport occurs only in eukaryotes?

Accepted Answer

A)  facilitated diffusion 
B)  ABC transport 
C)  siderophores 
D)  group translocation 
E)  endocytosis 
A)  facilitated diffusion 
B)  ABC transport 
C)  siderophores 
D)  group translocation 
E)  endocytosis

Question 12

E. coli reprograms during the stationary phase. What are some of the things it does to protect itself?

Accepted Answer

It decreases its size so that less nutri

Question 13

Metabolism of a microbe is best examined by growing the organism in a:

Accepted Answer

A)  defined medium 
B)  complex medium 
C)  spread plate 
D)  pour plate 
E)  cell culture 
A)  defined medium 
B)  complex medium 
C)  spread plate 
D)  pour plate 
E)  cell culture

Question 14

Some bacteria form environmentally resistant forms called __________.

Accepted Answer

A)  endospores 
B)  heterocysts 
C)  colonies 
D)  hyphae 
E)  actinomycetes 
A)  endospores 
B)  heterocysts 
C)  colonies 
D)  hyphae 
E)  actinomycetes

Question 15

All of the following are true about MacConkey medium except:

Accepted Answer

A)  It is selective. 
B)  It is differential. 
C)  It is both selective and differential. 
D)  It contains bile salts. 
E)  Lactose fermenters appear colorless. 
A)  It is selective. 
B)  It is differential. 
C)  It is both selective and differential. 
D)  It contains bile salts. 
E)  Lactose fermenters appear colorless.

Question 16

When using the LIVE/DEAD staining procedure, how can you distinguish live and versus dead cells and why do they appear different colors?

Accepted Answer

Live cells will appear green and dead ce

Question 17

A problem with __________ of cell number is that dead cells also scatter light.

Accepted Answer

A)  direct microscopic counts 
B)  viable counts 
C)  spread plate counts 
D)  pour plate counts 
E)  optical density measurements 
A)  direct microscopic counts 
B)  viable counts 
C)  spread plate counts 
D)  pour plate counts 
E)  optical density measurements

Question 18

Which of the following statements is false about the E. coli phosphotransferase system (PTS)?

Accepted Answer

A)  The EnzI complex in the cytoplasm is shared between all PTS transporters. 
B)  The EnzII complex is specific to the sugar being transported. 
C)  The phosphate group transferred to the sugar comes from phosphoenolpyruvate. 
D)  The PTS transport requires energy in the form of ATP. 
E)  One cannot say that the PTS transports a sugar against its concentration gradient. 
A)  The EnzI complex in the cytoplasm is shared between all PTS transporters. 
B)  The EnzII complex is specific to the sugar being transported. 
C)  The phosphate group transferred to the sugar comes from phosphoenolpyruvate. 
D)  The PTS transport requires energy in the form of ATP. 
E)  One cannot say that the PTS transports a sugar against its concentration gradient.

Question 19

__________ intercalates between DNA bases, causing dead cells to stain red under a fluorescence scope.

Accepted Answer

A)  Propidium iodide 
B)  Syto-9 
C)  Ethidium bromide 
D)  Crystal violet 
E)  Safranin 
A)  Propidium iodide 
B)  Syto-9 
C)  Ethidium bromide 
D)  Crystal violet 
E)  Safranin

Question 20

The majority of nitrogen in soil and marine environments is fixed by:

Accepted Answer

A)  free-living bacteria 
B)  symbionts 
C)  E. coli 
D)  biofilm organisms 
E)  UV light 
A)  free-living bacteria 
B)  symbionts 
C)  E. coli 
D)  biofilm organisms 
E)  UV light

Exam 4: Bacterial Culture, Growth, and Development

Describe the differences between batch culture and growth in a chemostat. What are the advantages of a chemostat?

Mannitol salt agar (MSA) contains 7.5% NaCl, the carbohydrate mannitol and the pH indicator phenol red. Some organisms can ferment mannitol, producing acids as a by-product. Is this medium likely to be selective and/or differential? Explain.

Which of the following is NOT true about the substrate binding protein (SBP) of the ABC transport system?

During biofilm formation, as more and more cells bind to the surface, they begin sending signals to each other in a process called:

During which stage of bacterial growth is the culture growing exponentially?

All known microorganisms have a set of genes coding for __________, whose DNA sequences are highly conserved across the phylogenetic tree.

The most widely used solidifying agent is __________, which is derived from seaweed.

A cafeteria worker who fails to wash his hands thoroughly and fails to wear gloves inoculates a quiche with 4 E. coli when he uses his finger to test whether it is done. By the time you purchase the quiche, there are 128 E. coli cells in it. How many generations did the cells go through?

Why is iron so often a limiting nutrient when it seems to be so abundant and how can organisms overcome this problem?

Which form of transport occurs only in prokaryotes?

Which form of transport occurs only in eukaryotes?

E. coli reprograms during the stationary phase. What are some of the things it does to protect itself?

Metabolism of a microbe is best examined by growing the organism in a:

Some bacteria form environmentally resistant forms called __________.

All of the following are true about MacConkey medium except:

When using the LIVE/DEAD staining procedure, how can you distinguish live and versus dead cells and why do they appear different colors?

A problem with __________ of cell number is that dead cells also scatter light.

Which of the following statements is false about the E. coli phosphotransferase system (PTS)?

__________ intercalates between DNA bases, causing dead cells to stain red under a fluorescence scope.

The majority of nitrogen in soil and marine environments is fixed by:

Microbial Life: Origin and Discovery

Observing the Microbial Cell

Cell Structure and Function

Environmental Influences and Control of Microbial Growth

Virus Structure and Function

Genomes and Chromosomes

Transcription, Translation, and Bioinformatics

Gene Transfer, Mutations, and Genome Evolution

Molecular Regulation

Viral Molecular Biology

Molecular Techniques and Biotechnology

Energetics and Catabolism

Respiration, Lithotrophy, and Photolysis

Biosynthesis

Food and Industrial Microbiology

Origins and Evolution

Bacterial Diversity

Archaeal Diversity

Eukaryotic Diversity

Microbial Ecology

Microbes and the Global Environment

Human Microbiota and Nonspecific Host Defenses

The Adaptive Immune Response

Microbial Pathogenesis

Microbial Diseases

Antimicrobial Chemotherapy

Clinical Microbiology and Epidemiology

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